Smoking articles

ABSTRACT

A smoking article comprising at least two of: (a) a tobacco blend comprising one or more tobaccos or tobacco grades with low TSNA and/or metal content; (b) a tobacco blend that has been treated to remove polyphenols and/or peptides; (c) a tobacco substitute sheet comprising a non-combustible inorganic filler, a binder and an aerosol generating means; (d) a high activity carbon comprising a polymer-derived carbon material; and (e) an amine-functionalised chelating resin.

TECHNICAL FIELD

The present invention relates to smoking articles and, in particular, tosmoking articles which combine two or more technological applicationsthat individually reduce the machine measured yields of specificconstituents or groups of constituents in mainstream smoke.

BACKGROUND

Tobacco smoke is a complex, dynamic mixture of more than 5000 identifiedconstituents of which approximately 150 have been documented as beingundesirable. The constituents are present in the mainstream smoke (MS)which is inhaled by a smoker and are also released between puffs asconstituents of sidestream smoke (SS).

In 2001 the Institute of Medicine (IOM) reported that, since smokingrelated diseases were dose-related, and because epidemiologic studiesshow reduction in the risk of smoking related diseases followingcessation, it might be possible to reduce smoking related risks bydeveloping potential reduced-exposure products (PREPs). These theydefined as: (1) products that result in the substantial reduction inexposure to one or more tobacco toxicants; and (2) if a risk reductionclaim is made, products that can reasonably be expected to reduce therisk of one or more specific diseases or other adverse health effects(Stratton et al, 2001). To date, no combustible cigarette product hasbeen shown to meet the general requirements outlined by the IOM.

The IOM and other groups (Life Sciences Research Office (LSRO) 2007;World Health Organisation (WHO) 2007) describe a number of stages ofactivity which are likely to be required for a combustible tobaccoproduct to be recognised as a PREP; however, the detailed approach andstages required to provide relevant data have yet to be agreed amongstthe scientific community. For example, some groups have proposed MSyield limits for specific smoke constituents and others have suggestedthat biomonitoring should play a role in this assessment

Much research has been done into the reduction of specific MSconstituents over recent years. Approaches have targeted different partsof the smoking article. There have been efforts to reduce the levels ofor to remove certain compounds from the starting material, for exampleby genetic engineering or by blending of specific tobaccos. Tobaccotreatments have sought to reduce or remove compounds from tobaccomaterial prior to incorporation into the smoking article. Various waysof “diluting” the tobacco in the tobacco rod of a smoking article havebeen attempted, using various types of diluents or fillers. Otherapproaches have involved ventilation of the smoking article, whereambient air is drawn into the smoking article to dilute the MS.Filtration is obviously another area where much work has been done toenhance the removal of MS constituents as they pass through the filtersection of the smoking article. All of these individual measures havebenefits, but they generally only address a small part of the picture.

A further issue to be addressed is the importance of producing a productwhich is acceptable to the consumer. Much of the sensory impact of aconventional smoking article is based upon the constituents of the MS.Removing some of these has the potential to provide the smoker with anunsatisfactory smoking experience.

There is, therefore, a challenge to provide a smoking article whichshows significant reduction in emissions of all MS constituentsconsidered to be undesirable. However, individual measures to reducecertain constituents will frequently give rise to no reduction in otherconstituents and, in some cases, even an increase in the levels ofothers.

Overall reductions in smoking machine measured toxicant yields can beachieved by diluting the smoke using filter ventilation or usingcigarette papers with high permeability, and, in the case of toxicantsthat are associated with the particulate phase of smoke, by increasingthe filtration efficiency of the filter. For many years, governments andpublic health authorities in various parts of the world considered lowerISO tar yielding cigarettes as a way to reduce the health risks ofsmoking for those smokers who do not quit smoking. However, this productmodification approach has more recently been highly criticised. TheStudy Group on Tobacco Product Regulation (TobReg) of the World HealthOrganization has recently proposed a regulatory approach that wouldlimit the yields of a selected group of specific smoke constituents.This group also recommended that the yields of constituents should belimited on the basis of their yields measured with an intense smokingmachine regime and determined per mg of nicotine.

Approaches to selectively reducing specific smoke constituents relativeto machine measured tar and nicotine yields are very dependent upon thephysiochemical nature of the individual constituents. Conventionalcigarette design parameters offer limited scope for relative reductionsin the smoke constituents. For example, by increasing the filterefficiency of a conventional cellulose acetate (CA) filter, theparticulate phase constituents are reduced with the tar and nicotine andlittle or no selective reduction occurs. And, since cellulose acetatefilters have little or no effect on volatile constituents, increasingfiltration efficiency increases the ratios of their yields relative totar and nicotine.

Increasing filter ventilation has varied effects on the smokeconstituents. The absolute yields of all the smoke constituents arereduced, but, relative to tar or nicotine, yields of most of theparticulate phase constituents are unchanged or may even be increased.The yields of some of the volatile constituents, such as ammonia andcarbon monoxide, are reduced relative to both tar and nicotine, whilethe relative yields of some of the semivolatile constituents such asphenols are increased.

Many of the volatile vapour phase components, such as the volatilealdehydes and hydrogen cyanide may be selectively reduced usingadsorbent materials in the filter such as activated charcoal or certainresins. However, permanent gases, such as carbon monoxide and nitricoxide, are not amenable to adsorption at room temperature, and toxicantsin the particulate phase cannot be selectively reduced by filtrationsince they are largely bound into the aerosol particles.

Since the 1950s, attempts have been made to selectively remove or reduceconstituents from cigarette smoke. Adsorption by porous adsorbents is apossible means of removing some of the volatile constituents from smoke.Active Carbon (AC) is a nonselective adsorbent which is widely used incigarette filters and can reduce a broad range of volatile smokeconstituents to a significant extent via physisorption. However, thedifficulty of this challenge should not be underestimated. Withcigarette smoke adsorbents there is a need to operate under high flowrate conditions (approximately 1 L per min for typical machine-smokingconditions), and therefore very short contact times between smokeconstituent and filter adsorbent (of the order of milliseconds).Adsorbents also need to function at the gas-solid interface (i.e. not insolution) and in the presence of thousands of other chemicals in bothvapour and particulate phases. Adsorbent surfaces are also susceptibleto blocking by condensing smoke aerosol particles. For permanent gases,and smoke constituents with high vapour pressures at ambienttemperatures such as formaldehyde, acetaldehyde or HCN, physicaladsorption has been found to be less effective and alternative routesare required.

Cigarette smoke contains a number of volatile aldehydes, both saturatedcompounds such as formaldehyde, acetaldehyde, propionaldehyde andbutyraldehyde, and unsaturated compounds such as acrolein andcrotonaldehyde. Carbonyls in cigarette smoke are mainly generated bycombustion of a number of tobacco constituents, mostly carbohydrates. Inparticular it is thought that sugars are major sources of formaldehydein cigarette smoke. Cellulose has been suggested to be the majorprecursor of mainstream smoke acetaldehyde. There are some datasuggesting that glycerol, a material sometimes added to tobacco as ahumectant, is an additional precursor for acrolein. Although the boilingpoint of formaldehyde is sub-ambient, 30% of formaldehyde in themainstream smoke exiting a filtered cigarette resides in the particulatephase and thus is not available for selective filtration at roomtemperature. Due to the presence of water vapour, formaldehyde in theparticulate phase of smoke exists as the hydrated form, CH₂(OH)₂.Acetaldehyde, one of the highest yield constituents of cigarette smoke,exists at or around its boiling point at ambient temperatures, andtherefore has a very high vapour pressure. The combination of these twofactors makes substantial removal of acetaldehyde from a smoke stream byfilter additives a major challenge.

A promising approach to achieving substantial specific reductions inparticulate constituents from a conventionally structured cigarette isto modify the tobacco. Substitution of different tobacco varieties intothe blend can have an impact on yields of several smoke constituents.For example there are higher yields of the nitrogen containing smokeconstituents from burley tobacco than from flue cured or oriental, andhigher yields of formaldehyde and catechol from flue-cured tobaccos.However, decreases in one constituents or set of constituents are oftenoffset by increases in other constituents. To avoid this it would beuseful to be able to identify and remove precursors to smokeconstituents from the tobacco leaf.

With the exception of the metallic constituents (chromium, nickel,arsenic, selenium, cadmium, mercury and lead) and some of the tobaccospecific nitrosamines (TSNAs), such as NAT and NAB, which aretransferred directly from the leaf, the majority of the smokeconstituents are formed by pyrosynthesis from the leaf components. Thus,the major precursors for the volatile carbonyls, benzo(a)pyrene, carbonmonoxide, benzene and toluene are the structural carbohydrates such aspectin and cellulose as well as the sugars. The nitrogenous smokeconstituents are formed from nitrogenous precursors in the leaf, andthere is considerable evidence that protein and amino acid combustioncontributes to the generation of several nitrogen containing smokeconstituents on the Health Canada list. Proteins and amino acids havebeen reported to be precursors for hydrogen cyanide, pyridine andquinoline, 2-aminonaphthalene and 4-aminobiphenyl. Tobacco protein isalso strongly correlated with the formation of mutagenic heterocyclicamines and the resulting mutagenicity of smoke condensate in the TA98Ames assay.

The polyphenols in tobacco are major precursors for phenolic smokecompounds. Chlorogenic acid, the most abundant polyphenol in flue-curedtobacco, is a major precursor for phenol, catechol and the substitutedcatechols, while hydroquinone has also been reported as a chlorogenicacid pyrolysis product. Rutin and caffeic acid also generate catecholand substituted catechols on pyrolysis but because of their lowconcentrations in tobacco and because of their lower pyrolytic yieldstheir contributions to catechol in flue-cured tobacco smoke are muchless than chlorogenic acid. Resorcinol is known to be a major productfrom pyrolysis of rutin.

DETAILED DESCRIPTION

The present invention provides combinations of bespoke tobacco blendswith bespoke adsorbent filter additives, which result in a smokingarticle having a significant reduction in mainstream smoke constituentsconsidered to be undesirable.

More specifically, the present invention provides a smoking articlecomprising at least two of:

-   -   (a) a tobacco blend comprising one or more tobaccos or tobacco        grades with low TSNA and/or metal content;    -   (b) a tobacco blend that has been treated to remove polyphenols        and/or peptides (soluble and insoluble);    -   (c) a tobacco substitute sheet comprising a non-combustible        inorganic filler, a binder and an aerosol generating means;    -   (d) a high activity carbon comprising a polymer-derived carbon        material; and    -   (e) an amine-functionalised chelating resin.

In a preferred embodiment, the smoking articles according to theinvention have a reduction in at least 75%, preferably at least 90% andmore preferably in all of the key constituents of mainstream smoke, asdefined herein.

The so-called “key constituents” of MS referred to in connection withthe present invention are those smoke constituents which have beenidentified in the literature as being undesirable (see, for example, TheScientific Basis of Tobacco Product Regulation: Report of a WHO StudyGroup (2007) WHO Technical Report Series 945, Geneva) and/or those whoseyields have been analysed in the data provided herein (see, for example,Tables 6, 7 and 8).

The reduction is preferably determined using one of the smoking machineconditions set out in Table 3. Preferably, the reduced yields aremeasured under Health Canada Intense smoking machine conditions.

The reduction in yield of the key constituents is preferably at least 5%or at least 10% or more.

Preferably, where the smoking articles of the present invention includea tobacco blend comprising one or more tobaccos or tobacco grades withlow TSNA and/or metal content, they further comprise two or more othertechnologies listed as (b) to (e).

BRIEF DESCRIPTION OF FIGURES

In order that the invention may be more fully understood, aspects andembodiments thereof will be described, by way of non-limiting exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 shows Table 2, setting out the cigarette construction details.

FIG. 2 shows Table 4, setting out the major constituent yields of testcigarettes to using different smoking machine condition.

FIG. 3 shows Table 5, setting out the blend metal and tobacco-specificnitrosamine contents.

FIG. 4 shows Table 6, setting out the MS yields of metals and TSNAsmeasured under Health Canada Intense smoking machine conditions.

FIGS. 5A, 5B and 5C show Table 7, setting out the MS yields of othersmoke constituents measured under Health Canada Intense smoking machineconditions.

FIG. 6 shows Table 8, setting out the MS yields of carbonyl andmiscellaneous volatile and vapour phase smoke constituents in controland triple stage filter EC measured under Health Canada Intense smokingmachine conditions.

FIG. 7 shows Table 9, setting out the MS yields of carbonyl andmiscellaneous volatile and vapour phase smoke constituents in controland dual stage filter EC measured under Health Canada Intense smokingmachine conditions.

FIG. 8 shows Table 10, setting out the sidestream smoke yields under ISOsmoking machine conditions

FIG. 9 shows a comparison of HCI machine toxicant yields from ECs (1 mgISO) with those from published data sources.

FIG. 10 shows a comparison of HCI machine toxicant yields from ECs (6 mgISO) with those from published data sources.

FIG. 11 shows a comparison of Total Toxicant Yields (TTY) between ECyields and published HCI yield data.

FIG. 12 shows a comparison of total yields from a subset of toxicants(TSY) between EC yields and published HCI yield data.

FIG. 13 shows a comparison of total normalised toxicant yields (NTT)between ECs and published HCI yield data.

FIG. 14 shows a summary of the process by which high activitypolymer-derived carbon is prepared.

FIG. 15 shows Table 15, setting out the smoke and biomarker changes fortest products as compared with a control cigarette.

FIG. 16 shows the in vivo study design.

FIGS. 17 and 18 show the results of the in vivo study.

FIG. 19 shows a smoking article design according to an embodiment of theinvention.

Two low toxicant tobacco blends, featuring a tobacco substitute sheet(TSS) or a tobacco blend treatment (BT), were combined with filterscontaining an amine functionalised resin material (CR20L) and/or a highactivity carbon adsorbent (HAC) to generate three experimentalcigarettes (ECs). Mainstream smoke (MS) yields of smoke constituentswere determined under four different smoking machine conditions. HealthCanada Intense (HCI) machine smoking conditions gave the highest MSyields for nicotine-free dry particulate matter and for most smokeconstituents measured. Constituent yields from the ECs were comparedwith those from two commercial comparator (CC) cigarettes, threescientific control (SC) cigarettes and published data on 120 commercialcigarettes. The ECs were found to generate some of the lowest machineyields of constituents from cigarettes for which HCI smoke chemistry isavailable; these comparisons therefore confirm that the ECs generatereduced MS machine constituent yields in comparison to commercialcigarettes.

The first stage in the design of a cigarette-based PREP involved thedevelopment of technologies which reduce the yields of smokeconstituents. Experimental cigarettes (ECs) were assembled using thesetechnologies and then assessed for their constituent yields usingsmoking machines; comparison to relevant control and reference productsindicated the effectiveness of the cigarette design in generatingreduced yields of constituents. Those ECs which are found to reducesmoking machine measured yields of smoke constituents, in comparison toreference products, are termed “reduced machine-yield prototypes”(RMYPs).

The inventors have described different individual technologicalapproaches to the reduction of constituents in cigarette smoke, one ofwhich involves the selection of tobacco blend components to provide ablend with reduced levels of the known precursors of undesirable smokeconstituents, two of which modify the tobacco and two of which modifythe cigarette filter. The tobacco blend (TB), the tobacco-substitutesheet material (TSS) and the tobacco blend treatment (BT) reduce thegeneration of constituents at source within the burning cigarette. Thetwo filter technologies, an amine functionalised resin material (CR20L)and a high activity, polymer-derived, carbon adsorbent (HAC), removevolatile species from the smoke stream after formation. Thesetechnologies are discussed in greater detail below (in Section 2.1).

Tobacco Blend

This involves the selection of tobacco blend components that exhibit lowlevels of the precursors of undesirable smoke constituents, such asTSNAs and metals. For example, the levels of TSNAs may be reduced byusing specific (such as lighter) tobacco blends and by selecting partsof the tobacco plant that are low in nitrate, a precursor of TSNAs. Theperson skilled in the art would be well aware of the ways in which theblending process may be adapted to provide a tobacco blend having thesedesired properties.

The tobacco blend may also comprise expanded tobacco, which is cuttobacco that has been expanded to reduce the mass of tobacco burnt in acigarette. The expansion processes are similar to those used to makepuffed rice snack food. One process used is called dry-ice expandedtobacco (DIET) and involves permeating the tobacco leaf structure withliquid carbon dioxide before warming. The resulting carbon dioxide gasforces the tobacco to expand. Some of the commercially available tobaccobrands with low ISO tar yields use some proportion of expanded tobaccoin the overall blend.

Tobacco Blend Treatment

Treated tobacco blends are described herein which have been treated byprocesses that allow the removal of protein and polyphenols fromtobacco, with a beneficial effect on the smoke toxicant yields. Thetobacco treatment was carried out on cut, flue-cured tobacco, andinvolved extraction of the tobacco with water followed by treatment withan aqueous protease enzyme solution. After treatment of the tobaccoextract with adsorbents and concentration, the solubles were re-appliedto the extracted tobacco. The treated tobacco retained the structure ofthe original tobacco and was made into cigarettes using conventionalcigarette making equipment, without the need for reconstitution into asheet material.

Tobacco Substitute Sheet

Another approach to reducing smoke toxicant yields is to dilute thesmoke with glycerol and it is proposed to include up to 60% of aglycerol-containing “tobacco substitute” sheet in cigarettes. Analysisof mainstream smoke from such experimental cigarettes showed reductionsin yields of most measured constituents, other than some volatilespecies.

Amine-Functionalised Resin Material

It has been found that chemisorption is capable of removing highvolatility aldehydes and HCN from mainstream cigarette smoke. A weaklybasic macroporous polystyrene resin cross-linked with divinyl benzene,with surface amine functionality, was identified and assessed as acigarette filter additive. The material, manufactured by MitsubishiChemical Corporation is normally supplied in bead form in an aqueousenvironment and sold under the trade name Dialon®CR20 (hereafterreferred to as CR20). This material offers the potential for thenucleophilic capture of aldehydes from mainstream smoke, and due to itsweakly basic nature it may also be used for the removal of HCN from MS.

The amine-functionalised chelating resin material may be incorporatedinto the filter of a smoking article in a cavity, or dispersed(dalmation style) throughout the filter material (such as celluloseacetate) in the whole or a section of the filter.

High Activity Carbon

A high activity material comprising spherical particles ofpolymer-derived carbon was prepared by a propriety process (Von Bl{dotover (u)}cher and De Ruiter 2004; Von Blucher et el 2006; Böhringer andFichtner 2008) and was available from Blücher GmbH (Germany). Thepolymer-derived material is approximately twice as effective, ingeneral, at removing volatile cigarette smoke toxicants than the coconutshell-derived carbon commonly used in contemporary carbon filteredcigarette products. The polymer-derived carbon performed well at bothISO and HCI smoking regimes and with regular and smaller circumferencecigarettes. Limitations were also observed under higher flow-ratesmoking conditions in the removal of acetaldehyde.

The high activity carbon may be incorporated into the filter of asmoking article in a cavity, or dispersed (dalmation style) throughoutthe filter material (such as cellulose acetate) in the whole or asection of the filter.

The present invention provides ECs made using combinations of the blendand filter technologies described. The goal of the study of these ECswas to assess whether these technologies could be combined intoprototypes which reduce machine yields of toxicants in comparison tocommercial products, and have the potential to reduce exposure ofsmokers to toxicants in human smoking.

Testing the ECs under a variety of smoking machine conditions andanalysing the yields of smoke constituents on a per cigarette basis andas a ratio per milligram of nicotine yield, permits comparisons withrelevant commercial comparator cigarettes, and also to a wide range ofproducts reported in the literature. The results presented in this workdemonstrate that the development of combustible RMYPs is feasible.

2. Materials and Methods 2.1 Design of Experimental, Control andComparator Cigarettes

The ECs were constructed from combinations of blend and filtertechnologies that were developed to reduce specific chemical classes ofsmoke toxicants or their precursors in tobacco (Table 1). For each ECindividual tobacco grades with low TSNA and metal contents were selectedand blended to provide a low toxicant starting point for the design ofexperimental cigarettes.

TABLE 1 Technologies used in the construction of experimental cigarettes(ECs). Technological Cigarette Potential Application ComponentDescription Reduction Tobacco Blend Blend Selection of tobacco SomeTSNAs (TB) blend components that and metals exhibit low levels of theprecursors of undesirable smoke constituents Tobacco BlendTobacco-substitute sheet Whole smoke Substitute reducing tobacco Sheet(TSS) combustibles and giving glycerol dilution of smoke Tobacco BlendBlend Protease treated tobacco, Nitrogen-based Treatment reducingprotein nitrogen constituents: (BT) and polyphenols in the aromaticblend amines, NAB, NAT, NNK, NNN; phenols Amine- Filter Amine group HCN,HCHO, functionalised functionalised resin acetaldehyde Resin Beadsincluded in filter stage and other (CR20L) carbonyls High ActivityFilter Polymer-derived, Vapour phase Carbon spherical carbon beadsconstituents (HAC) included in filter stage

Tobacco Blend Treatment

Briefly, the tobacco blend is subjected to an aqueous extraction stepand the extract is subsequently passed through two stages of filtrationto remove polyphenols and soluble peptides. The residual tobacco solidsare treated with protease to remove insoluble proteins. After washingand enzyme deactivation, the tobacco solids and filtered aqueous extractare re-combined. The treatment process results in reduced smoke yieldsof phenolics, aromatic amines, HCN, and a number of other nitrogenoussmoke constituents; however, there are also increases in the yields offormaldehyde and isoprene.

The tobacco material to be extracted may be strip, cut, shredded orground tobacco. In a preferred embodiment, the tobacco is shreddedtobacco. Other forms of tobacco may, however, be extracted using themethods described herein.

The tobacco material may be mixed with a solvent for extraction to forma slurry. The solvent may be added to the tobacco material in a ratio ofbetween 10:1 and 50:1, preferably between 20:1 and 40:1 and mostpreferably between 25:1 and 30:1 by weight. In a particularly preferredembodiment, the solvent is added to the tobacco material in a ratio of27:1 by weight.

The solvent may be an organic solution, but preferably is an aqueoussolution or is water. At the very start of the extraction process, thesolvent is usually water, but it can also contain alcohols such asethanol or methanol, or it can contain a surfactant. Other solventscould be used, depending on the particular constituents to be extractedfrom the tobacco.

The extraction may be performed at 15-85° C., and preferably isperformed at 65° C. It is preferable for the slurry to be continuallystirred during extraction, such that the tobacco remains in suspension.Extraction should be performed for between 15 minutes and two hours. Ina preferred embodiment, extraction is performed for approximately 20minutes.

During extraction, soluble tobacco components are removed from thetobacco material and enter solution. These include nicotine, sugars,some proteins, amino acids, pectins, polyphenols and flavours. Up toabout 55% of the initial tobacco weight may become solubilised. It isimportant that the pectins in the tobacco fibre remain cross-linkedthroughout the extraction and treatment process in order to maintain thefibrous structure of the tobacco. Accordingly, calcium may be added tothe solvent used to extract the tobacco and to any solutions used in thedownstream processing procedures.

Following extraction, the slurry may be drained to allow the liquidfiltrate (the “mother filtrate”) to be collected. Meanwhile, theinsoluble tobacco residue may be further extracted by counter-currentwashing as it is conveyed, so that as many soluble constituents aspossible are removed from the tobacco.

Fresh solvent may be applied to the tobacco and the filtrate (the “washfiltrate”) is collected. The wash filtrate may be recycled by beingapplied to the incoming tobacco residue traveling on the belt at anupstream point. The collection and upstream reapplication of washfiltrate to incoming tobacco residue may be repeated a number of times,preferably three, four or even five times. Thus, the final wash filtratethat is collected at the head of the belt may be concentrated in thosesoluble tobacco constituents that have been removed from the tobaccoresidue as it travels the length of the filter. The final wash filtratemay be further recycled by being added to fresh tobacco to form atobacco slurry, ready for extraction. For example, the final washfiltrate may be added into the tobacco mix tank where a tobacco slurryis formed prior to extraction. The extraction process may thus be acontinual process in which fresh tobacco is extracted using recycledwash filtrate. Only at start-up of this extraction process is tobaccoextracted with fresh solvent. Once the extraction process has begun, nofresh solvent is used in the extraction, but the solvent is solely madeup of recycled wash filtrate.

As the extraction process continues, the extract thus becomes moreconcentrated in soluble tobacco constituents. These constituents includethose that entered solution during primary extraction in the extractiontank (forming the mother filtrate), as well as those that enteredsolution during secondary extraction on the horizontal belt filter(forming the wash filtrate).

The final filtrate thus comprises both the mother and wash filtrates. Inso doing, the tobacco residue that results after filtration is devoid ofthose constituents that are soluble in the solvent used for extraction.The extracted tobacco may be squeezed at the end of filtration, so as toremove any excess liquid from it. The extracted tobacco emanating fromthe horizontal belt filter is thus typically in the form of a dewateredmat.

The final filtrate, hereinafter referred to as the tobacco extract, maybe subsequently processed to remove those constituents not desired inthe final tobacco product. Undesirable constituents include proteins,polypeptides, amino acids, polyphenols, nitrates, amines, nitrosaminesand pigment compounds. The levels of constituents which may beconsidered desirable, such as sugar and nicotine, may, however, remainunaffected so that the flavour and smoking properties of the extractedtobacco are comparable to those of the original material.

In a preferred embodiment, the tobacco extract is treated to removeproteins, polypeptides and/or amino acids. Up to 60% of the proteinscontained in the original tobacco material may be removed using aninsoluble adsorbent such as hydroxyapatite or a Fuller's Earth mineralsuch as attapulgite or bentonite. The tobacco extract is preferablytreated with bentonite, to remove polypeptides therefrom. Bentonite maybe added to the extract in an amount of 2-4% of the weight of tobaccoinitially extracted. Alternatively, the tobacco extract may be fed intoa tank containing a slurry of bentonite in water. A suitable slurrycontains approximately 7 kg of bentonite in approximately 64 kg water(quantities per hour), for example, 7.13 kg bentonite in 64.18 kg water(quantities per hour). In any case, the bentonite concentration shouldbe high enough to substantially reduce the protein content of thetobacco extract, but not so high as to additionally adsorb nicotine fromit. Bentonite treatment may also be effective in the removal of pigmentcompounds found in tobacco extract which, if not removed, tend to darkenthe extract after concentration. When sufficient bentonite is used totreat the extract, the reduced amount of pigment compounds may result ina product that is not overly darkened in appearance.

Following bentonite treatment, the tobacco extract may be purified fromthe slurry by centrifugation and/or filtration. The tobacco extract mayalso, or alternatively, be treated to remove polyphenols therefrom.

Polyvinylpolypyrrolidone (PVPP) is an insoluble adsorbent forpolyphenols, traditionally used in the brewing industry to removepolyphenols from beer. PVPP in an amount of 5-10% of the weight oftobacco initially extracted may be added to the extract. This amount ofPVPP is capable of removing between 50 and 90% of the polyphenols insolution. The optimum pH for removal of polyphenols from the tobaccoextract by PVPP is believed to be about 3. The efficiency of adsorptionby PVPP may therefore be increased by reducing the pH of the extract viathe addition of a suitable acid, such as hydrochloric acid.

As an alternative to using PVPP to adsorb the polyphenols, one or moreenzymes may be added to the tobacco extract to degrade the polyphenolstherein. A suitable enzyme is laccase (urishiol oxidase). The inventionis not, however, limited to methods for removing only proteins and/orpolyphenols from tobacco. Alternative or additional enzymes, agents oradsorbents may be used to remove other undesirable tobacco constituentsfrom the tobacco extract. Examples of further undesirable tobaccoconstituents that could be removed from the extract include nitrates,amines and nitrosamines.

If a plurality of constituents is to be removed from the tobaccoextract, a number of tanks may be set up in series, each one comprisinga different enzyme, agent or adsorbent, in order for a chosen complementof undesirable constituents to be removed. Alternatively, a single tankmay contain a plurality of enzymes, agents or adsorbents so that theundesirable constituents may be removed min a single step. For example,a bentonite or PVPP holding tank could comprise one or more additionalenzymes, agents or adsorbents so as to remove not only protein orphenols from the tobacco, but one or more further undesirableconstituents also.

Following treatment of the tobacco extract to remove the selectedundesirable constituents, the extract is preferably concentrated to asolids concentration of between 20 and 50% by weight. Concentrations ofup to 10% solids are most efficiently achieved using reverse osmosis. Afurther concentration to approximately 40% solids may be achieved bymeans of a falling film evaporator. Other methods of concentration canbe used and will be known to a person skilled in the art. Theconcentrated tobacco extract may be subsequently recombined with theextracted tobacco.

The tobacco, having been extracted in an aqueous solution as discussedabove, however, is preferably further extracted to remove one or morefurther undesirable constituents before being recombined with theconcentrated tobacco extract.

Further extraction of the tobacco may be performed using an enzymespecifically selected for removal of the constituent of choice. In apreferred embodiment, the enzyme is a proteolytic enzyme for removal ofprotein from the tobacco. The enzyme is preferably a bacterial or fungalenzyme and, more preferably, is an enzyme used commercially in the foodand detergent industries. The enzyme may be selected from the groupconsisting of Savinase™, Neutrase™, Enzobake™ and Alcalase™, which areall available from Novozymes A/S. The proteolytic enzyme is preferablyadded to the tobacco in an amount of between 0.1 and 5% by weight of thetobacco material. For example, Savinase™ may be added to the tobacco inan amount of approximately 1% by weight. The tobacco may be reslurriedin a solution of the chosen enzyme. The ratio of water to tobacco in theslurry should be between 10:1 and 50:1, preferably between 20:1 and 40:1and most preferably between 25:1 and 30:1 by weight. In a particularlypreferred embodiment, the ratio of water to tobacco is 27:1 by weight.

The pH of the tobacco/enzyme mixture should be that which promotesoptimal enzyme activity. Accordingly, it may prove convenient to feedthe dewatered mat of tobacco into a tank in which the pH is adjusted,for example, by the addition of a base such as sodium hydroxide. ThepH-adjusted tobacco may then be fed into an enzyme dosing tank formixing with the enzyme of choice. The tobacco/enzyme mixture maysubsequently be fed into a plug flow reactor, where the enzymicextraction is performed. The enzymic extraction should be carried out atthe temperature promoting optimal enzyme activity. Preferably, a narrowtemperature range, such as 30-40° C., should be used to avoid denaturingthe enzyme. The optimum working conditions when Savinase™ is the chosenenzyme are 57° C. and pH 9-11. The enzymic extraction should be carriedout for at least 45 minutes; any shorter duration is believed to beinsufficient for a proteolytic enzyme to degrade tobacco proteins.

Of course, multiple enzymic extractions could be carried out if thereare multiple constituents to be removed from the tobacco. These could beperformed in series or multiple enzymes could be added to the tobacco ina single treatment step.

It also remains possible for the enzyme to be included in the very firstextraction step in the treatment process, rather than forming asubsequent separate extraction step.

Following enzymic extraction, the insoluble tobacco residue may bewashed with a salt solution, preferably a sodium chloride solution, torinse it free of enzyme. Salt rinsing may be performed in a sequential,counter-current fashion.

Salt and water rinsing, however, may not be sufficient to remove all ofthe enzyme from the tobacco. The washed tobacco may also be treated todeactivate any residual enzyme remaining in the tobacco following thesalt and water rinses. This may be done by steam treating the tobaccosufficiently to deactivate the enzyme, but not so much that the tobaccoloses its fibrous form. In an embodiment, steam treating is carried outat 98° C. for four minutes, but the residence time may be increased to10 minutes or so if desired. Alternatively, the tobacco may be heattreated to deactivate the enzyme, for example by microwaving or bakingthe tobacco. In another embodiment, the enzyme may be deactivated bychemical denaturation; steps should however be taken to remove thechemical from the tobacco.

The processed tobacco may then be recombined with the concentratedtobacco extract. Adding the treated extract back to the extractedtobacco ensures retention of water soluble flavour components of tobaccoand nicotine in the final product. Recombination therefore results in atobacco product that has similar physical form and appearance, taste andsmoking properties to the original material, but with substantiallyreduced levels of protein, polyphenols or other constituent(s) ofchoice. Recombination may be achieved by spraying the tobacco extractonto the tobacco. The amount of the original extract being recombinedwith the processed tobacco depends upon the amount that was lost duringtreatment of the extract to remove selected constituents, and will varyfrom one type of tobacco to the next.

A standard drying process may be used to dry the treated tobacco, eitherbefore, during or after recombination with the treated tobacco extract.The starting moisture content of the treated tobacco is typicallyapproximately 70-80%. In a preferred embodiment, the moisture contentafter drying should be approximately 14%. A heated dryer, such as anapron dryer, may be used to reduce the starting moisture content in thetobacco to approximately 30%. A second heated dryer, such as an airdryer, may then be used to further reduce the moisture content toapproximately 14%.

The final dried product may subsequently be processed into a finishedform, such as a sheet, which, when shredded, can form all or part of acigarette filler. Owing to as much as 30% of the original constituentsof tobacco being removed therefrom during the extraction and treatmentprocess, however, the concentration of remaining constituents per unitweight of tobacco is increased in the finished product compared to theoriginal material. These constituents include cellulose, which, togetherwith sugars and starches, may produce harmful volatile materials such asacetaldehyde and formaldehyde in smoke when combusted.

Tobacco Substitute Sheet

Incorporation of the tobacco substitute sheet (TSS) into a tobacco blendreduces the quantity of tobacco in a cigarette, thereby diminishing theoverall potential for the cigarette to generate toxicants. The TSS alsocontains glycerol and, when heated, the TSS releases glycerol into thesmoke stream contributing to the total amount of particulate smoke,measured as nicotine-free dry particulate matter (NFDPM, also known as“tar”). As most cigarettes are designed to meet a specific NFDPM yieldvalue, incorporation of glycerol into the smoke stream effectivelyresults in a reduced contribution of the tobacco combustion products tothe overall NFDPM value: this process is termed “dilution.” Theincorporation of TSS into cigarettes results in reductions in a widerange of smoke constituents, including both particulate and vapour phasetoxicants. In vitro toxicological tests showed reductions in theactivity of smoke particulates in proportion to their glycerol content.Human exposure to nicotine was reduced by a mean of 18% as determined byfilter studies and by 14% using 24 hour urinary biomarker analysis.Smoke particulate exposures were reduced by a mean of 29% in filterstudies and by similar amounts based on urinary4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol concentrations. Theseresults show that reducing exposure to some smoke toxicants is possibleusing a tobacco substitute sheet.

According to the present invention, a smoking article may be preparedincluding a tobacco substitute sheet material comprising anon-combustible inorganic filler material, an alginic binder and aerosolgenerating means.

Advantageously the tobacco substitute sheet material comprises as themain components thereof, non-combustible inorganic filler, binder andaerosol generating means, with these three components togetherpreferably comprising at least 85% by weight of the tobacco substitutesheet material, preferably greater than 90%, and even more preferablytotal about 94% or more by weight of the tobacco substitute sheetmaterial. The three components may even be 100% of the tobaccosubstitute sheet material. The remaining components are preferably oneor more of colourant, fibre, such as wood pulp, or flavourant, forexample. Other minor component materials will be known to the skilledman. The tobacco substitute sheet material is therefore a very simplesheet in terms of its constituents.

As used herein, the term ‘tobacco substitute sheet material’ means amaterial which can be used in a smoking article. It does not necessarilymean that the material itself will necessarily sustain combustion. Thetobacco substitute sheet material is usually produced as a sheet, thencut. The tobacco substitute sheet material may then be blended withother materials to produce a smokable filler material.

The present invention further provides a smoking article comprising awrapped rod of a smokable filler material, the smokable filler materialconsisting of a blend which incorporates tobacco substitute sheetmaterial comprising a non-combustible inorganic filler, an alginicbinder and aerosol generating means, the smoking article having anaerosol transfer efficiency ratio of greater than 4.0. As used herein,the aerosol transfer efficiency is measured as the percentage aerosol inthe smoke divided by the percentage aerosol in the smokable fillermaterial. Preferably the aerosol transfer efficiency is greater than 5,and more preferably greater than 6.

The smokable filler material used in the smoking articles of the presentinvention may comprise a blend consisting of not more than 75% by weightof the tobacco substitute sheet material.

Preferably the inorganic filler material is present in the range of60-90%, and is more preferably greater than 70% of the final sheetmaterial. Advantageously the inorganic filler material is present atabout 74% by weight of the final sheet material, but may be present athigher levels, for example, 80%, 85% or 90% by weight of the final sheetmaterial.

The non-combustible filler advantageously comprises a proportion ofmaterial having a mean particle size in the range of 500 μm to 75 μm.Preferably the mean particle size of the inorganic filler is in therange of 400 μm to 100 μm, and is more than 125 μm, and preferably morethan 150 μm. Advantageously the mean particle size is at or about 170μm, and may be in the range of 170 μm to 200 μm. This particle size isin contrast to that conventionally used for food grade inorganic fillermaterials in alternative tobacco products, namely a particle size ofabout 2-3 μm. The range of particle size seen for each inorganic fillerindividually may be from 1 μm-1 mm (1000 μm). The inorganic fillermaterial may be ground, milled or precipitated to the desired particlesize.

Advantageously the inorganic filler material is one or more of perlite,alumina, diatomaceous earth, calcium carbonate (chalk), vermiculite,magnesium oxide, magnesium sulphate, zinc oxide, calcium sulphate(gypsum), ferric oxide, pumice, titanium dioxide, calcium aluminate orother insoluble aluminates, or other inorganic filler materials. Thedensity range of the materials is suitably in the range of 0.1 to 5.7g/cm³. Advantageously, the inorganic filler material has a density thatis less than 3 g/cm³, and preferably less than 2.5 g/cm³, morepreferably less than 2.0 g/cm³ and even more preferably less than 1.5g/cm³. An inorganic filler having a density of less than 1 g/cm³ isdesirable. A lower density inorganic filler reduces the density of theproduct, thus improving the ash characteristics.

If a combination of inorganic filler materials is used, one or more ofthe fillers may suitably be of a small particle size and another may beof a larger particle size, the proportions of each filler being suitableto achieve the desired mean particle size. The static burn rate requiredin the finished smoking article may be achieved using an appropriateblend of tobacco and tobacco substitute sheet material in the smokablefiller material.

Preferably the inorganic filler material is not in agglomerated form.The inorganic filler material should require little pre-treatment, otherthan perhaps size gradation, before use. Preferably the binder ispresent in the range of about 5-13%, more preferably less than 10% andeven more preferably less than 8%, by weight of the final fillermaterial. Advantageously the binder is about 7.5% by weight or less ofthe final sheet material. Advantageously, if the binder is a mixture ofalginate and non-alginate binders, then preferably the binder iscomprised of at least 50% alginate, preferably at least 60% alginate andeven more preferably at least 70% alginate. The amount of combinedbinder required may suitably decrease when a non-alginate binder isutilised. The amount of alginate in a binder combination advantageouslyincreases as the amount of combined binder decreases. Suitable alginicbinders include soluble alginates, such as ammonium alginate, sodiumalginate, sodium calcium alginate, calcium ammonium alginate, potassiumalginate, magnesium alginate, triethanol-amine alginate and propyleneglycol alginate. Other organic binders such as cellulosic binders, gumsor gels can also be used in combination with alginic binders. Suitablecellulosic binders include cellulose and cellulose derivatives, such assodium carboxymethylcellulose, methyl cellulose, hydroxypropylcellulose, hydroxyethyl cellulose or cellulose ethers. Suitable gumsinclude gum arabic, gum ghatti, gum tragacanth, Karaya, locust bean,acacia, guar, quince seed or xanthan gums. Suitable gels include agar,agarose, canageenans, furoidan and furcellaran. Starches can also beused as organic binders. Other suitable gums can be selected byreference to handbooks, such as Industrial Gums, E. Whistler (AcademicPress). Much preferred as the major proportion of the binder are alginicbinders. Alginates are preferred in the invention for their neutraltaste character upon combustion.

Preferably the aerosol generating means is present in the range of5-20%, more preferably is less than 15%, is even more preferably greaterthan 7% and even more preferably is greater than 10%. Preferably theaerosol generating means is less than 13%. Most preferably the aerosolgenerating means is between 11% and 13%, and may advantageously be about11.25% or 12.5%, by weight of the final sheet material. Suitably theamount of aerosol generating means is selected in combination with theamount of tobacco material to be present in the blend comprising thesmokable filler material of a smoking article. For example, in a blendcomprising a high proportion of sheet material with a low proportion oftobacco material, the sheet material may require a lower loading levelof aerosol generating means therein. Alternatively in a blend comprisinga low proportion of sheet material with a high proportion of tobaccomaterial, the sheet material may require a higher loading level ofaerosol generating means therein.

Suitable aerosol generating means include aerosol forming means selectedfrom polyhydric alcohols, such as glycerol, propylene glycol andtriethylene glycol; esters, such as triethyl citrate or triacetin, highboiling point hydrocarbons, or non-polyols, such as glycols, sorbitol orlactic acid, for example. A combination of aerosol generating means maybe used.

An additional function of the aerosol generating means is theplasticising of the sheet material. Suitable additional plasticisersinclude water. The sheet material may suitably be aerated. The castslurry thereby forms a sheet material with a cellular structure.

Advantageously the or a proportion of the aerosol generating means maybe encapsulated, preferably micro-encapsulated, or stabilised in someother way. In such cases the amount of aerosol generating means may behigher than the range given.

Advantageously the smoking material comprises a colourant to darken thematerial and/or a flavourant to impart a particular flavour. Suitableflavouring or colourant materials, subject to local regulations, caninclude cocoa, liquorice, caramel, chocolate or toffee, for example.Finely ground, granulated or homogenised tobacco may also be used.Industry approved food colorants may also be used, such as E150a(caramel), E151 (brilliant black BN), E153 (vegetable carbon) or E155(brown HT). Suitable flavourants include menthol and vanillin, forexample. Other casing materials may also be suitable. In thealternative, the presence of vermiculite or other inorganic fillermaterials may give a darker colour to the tobacco substitute sheetmaterial. Preferably the colourant is present from 0-10% and may be asmuch as 5-7% by weight of the final tobacco substitute sheet material.Advantageously the colourant is less than 7%, preferably less than 6%and more preferably less than 5% of the final tobacco substitute sheetmaterial. Much preferred is use of colourant at less than 4%, less than3% and less than 2%. Cocoa may suitably be present in a range of 0-5%and liquorice may be present in a range of 0-4%, by weight of the finaltobacco substitute sheet material. When the colourant is cocoa orliquorice, for example, the minimum amount of cocoa to obtain thedesired sheet colour is about 3% and for liquorice is about 2%, byweight of the final tobacco substitute sheet material. Similarly,caramel may suitably be present in a range of 0-5%, preferably less thanabout 2% by weight of the final tobacco substitute sheet material, andmore preferably about 1.5%. Other suitable colorants include molasses,malt extract, coffee extract, tea resinoids, St. John's Bread, pruneextract or tobacco extract. Mixtures of colorants may also be used.

If permitted under local regulations, flavourants may also be added toalter the taste and flavour characteristics of the tobacco substitutesheet material. Advantageously, if a food dye is utilised in thealternative it is present at 0.5% by weight or less of the final tobaccosubstitute sheet material. The colourant may alternatively be dustedinto the sheet after sheet manufacture.

Fibres, such as cellulose fibres, for example wood pulp, flax, hemp orbast could be added to provide the sheet material with one or more of ahigher strength, lower density or higher fill value. Fibres, if added,may be present in the range of 0.5-10%, preferably less than 5% and evenmore preferably less than about 3% by weight of the final sheetmaterial. Advantageously there is no fibrous material present in thesheet material, cellulosic or otherwise.

Advantageously the tobacco substitute sheet material is a non-tobaccocontaining sheet. It shall be understood that at high levels of sheetmaterial inclusion in the blend, e.g. at greater than 75% by weight ofthe blend, the combustibility of the blend is poor. This may be overcomeby, for example, incorporating low levels of up to 5-10% granular carbonin the tobacco substitute sheet material. The carbon is preferably notan agglomerated carbonaceous material, i.e. the carbon is notpre-treated by mixing with another material to produce an agglomerate.

Preferably the tobacco substitute sheet material is blended with tobaccomaterial to provide smokable filler material. Preferably the tobaccomaterial components in the blend are high quality lamina grades.Advantageously the majority of the tobacco material is cut tobacco. Thetobacco material may comprise between 20-100% expanded tobacco of a highorder expansion process, such as DIET for example. The filling power ofsuch material is typically in the range of 6-9 cc/g (see GB 1484536 orU.S. Pat. No. 4,340,073 for example).

Preferably the blend comprises <30% of other blend components apart fromlamina, the other blend components being stem cut rolled stem (CRS),water treated stem (WTS) or steam treated stem (STS) or reconstitutedtobacco. Preferably the other components comprise <20%, more preferably<10% and even more preferably <5% of the final weight of the tobaccomaterial.

Suitably a smoking article according to the invention comprises tobaccomaterial being treated with aerosol generating means. The tobaccomaterial may be treated with aerosol generating means, but this is notessential for all blends of tobacco material and sheet material.

The amount of aerosol generating means added to the tobacco is in therange of 2-6% by weight of the tobacco. The total amount of aerosolgenerating means in the blend of tobacco material and sheet materialafter processing is advantageously in the range of 4-12% by weight ofthe smokable material, preferably less than 10% and preferably more than5%.

High Activity Carbon

The polymer-derived, high activity carbon granules used in the dual andtriple stage filters possesses a pore structure different from thecarbon commonly used in commercial cigarettes, which is typicallyderived from coconut shells. As a result it has superior adsorptioncharacteristics for a range of volatile smoke toxicants.

The spherical particle shape polymer-derived carbon was prepared by apropriety process (Von Blucher and De Ruiter 2004, Von Bl{dot over(u)}cher et el 2006, Bohringer and Fichtner 2008), as depicted in FIG.14. The polymer-derived active carbon is produced using a batch processwith indirect heated rotary kilns, under reduced pressure in an ineitatmosphere. After preparation of the spherical polymer feedstock thematerial is thermally stabilised using an excess of oleum. Subsequently,the material is slowly heated to 500° C., resulting in the release ofpredominantly SO₂ and H₂O and the carbonisation of the polymer. Theresulting carbon has an initial pore system which is not accessible fortypical adsorptives. To create a porous system capable for adsorption,the material is further heated to 900 to 1000° C. for activation withoxidising agents (steam). This establishes a pore system consistingmainly of micropores with pore sizes between 0.7 and 3 nm. Subsequentactivation with CO₂ leads to the formation of predominantly largermesopores in the range of 3 to 80 nm. Combining the steam and CO₂activation steps offers a flexible strategy for producing desired porecharacteristics.

The polymer-derived carbon, being a synthetic material, possesses a muchmore closely defined spherical shape, together with a more uniformparticle size. The polymer derived material possesses a lower density,and has a lower ash content reflecting the synthetic nature of thepolymer feedstock in comparison to a natural coconut shell as startingmaterials for the carbonization processes.

Most smoke constituents are adsorbed more effectively by thepolymer-derived carbon under the ISO regime than by activated coconutcarbon, with reductions of the order of 80-95% observed with smokeconstituents other than formaldehyde, acetaldehyde, hydrogen cyanide(HCN) and toluene (50-60% reductions). Under HCI conditions, cigaretteswith conventional coconut carbon provide reductions of the order of25-45% for most smoke constituents, other than acetaldehyde (16%). Thecigarettes including polymer-derived carbon reduce most smokeconstituent yields by 60-90%, other than acetaldehyde and HCN (15-30%).

Amine-Functionalised Resin Beads

DIAION® CR20 is a commercially available type of amine-functionalisedresin bead which may be used in the present invention (manufactured byMitsubishi Chemical Corporation). It has polyamine groups as chelatingligands which are bonded onto a highly porous crosslinked polystyrenematrix. CR20 shows large affinity for transition metal ions. The exacttype of amine groups produced by functionalization cannot be preciselycontrolled and several different types could be present on the resins.

Commercial grade CR20 (hereafter referred to as CR20C) was found to havea characteristic odour incompatible with conventional consumeracceptable cigarette smoke character when incorporated into cigarettes.However, modification to the synthesis conditions by Mitsubishisignificantly reduced the intensity of this odour, resulting in a“low-odour” grade of CR20 (hereafter referred to as CR20L). In thiswork, unless otherwise stated, all results obtained refer to CR20L. Thismaterial possessed a bead size of 600 mm, density of 0.64 g/cm³, a 15%by weight water content, and total exchange capacity of 0.92 meq/cm³.

Various other types of CR20 are made by Mitsubishi Chemical Corporation,to including CR20D and CR20HD. All of the different types or grades ofthe ion-exchange resin are encompassed by the term CR20 as used herein.

Some CR20 beads are provided in water and, to make them suitable for usein a cigarette filter application, it may be necessary to remove atleast some of the water. In one embodiment, the water is removed and thematerial is dried to approximately 15% or less moisture. In analternative embodiment, a higher moisture content may be acceptable inthe filter of smoking articles.

CR20, including specifically CR20L, may be incorporated into cigarettefilters. In comparison to filters containing conventional carbon, CR20Loffers superior reductions for HCN, formaldehyde and acetaldehyde.However, carbon is more efficient than CR20L in removing other volatileconstituents from a smoke stream.

Experimental Cigarettes

Cigarettes were constructed using these technologies targeting ISO NFDPM(tar) yields of 1 and 6 mg.

Three scientific control cigarettes were also manufactured to allow anevaluation to be made of the contribution of the filter technologies tosmoke constituent reductions from ECs. Two commercial comparatorcigarettes, a 1 mg ISO design and a 6 mg ISO design, were also used inthese studies. Comparisons with commercial brands were conducted becauserealistic control cigarettes are required to assess the success withwhich the different smoke constituent reduction technologies can bebrought together into a coherent and consumer acceptable cigarettedesign. Also, the use of commercial cigarettes allows examination of theextent with which constituent reductions can be realised againstreal-world cigarettes, rather than scientific controls. Finally, use ofcommercial reference products allows relevant comparisons to be made ofsensory acceptability and human exposure under real-world use.

The commercial comparator products were of similar machine smokedconstituent yields to the market leading brands at 1 mg and 6 mg (ISO)from Germany in 2007-8. BAT group comparator cigarettes were chosen,rather than the actual market leading brands, in order that fullinformation was available on blend and cigarette design characteristics,and to allow product masking to be conducted for human sensory andexposure evaluations. Samples of both commercial cigarettes weretherefore manufactured specially for these studies, without brandmarking or other identification, in order to support human smokingstudies.

2.2 Specifications for Experimental, Comparator and Control Cigarettes

Common features were used in the design of the ECs: all were constructedto the same basic dimensions, of 84 mm cigarette length (a 57 mm tobaccorod plus a 27 mm filter), 24.6 mm circumference and the filters were allbased on cellulose acetate (CA) fibres plasticized with triethylcitrate. Tobacco grades with low TSNA and metal contents were identifiedand combined for the tobacco blends used in these prototypes. Threedifferent experimental cigarettes were prepared, and the design featuresof the three ECs are summarised and compared with control cigarettes andcommercial comparators in Table 2 (shown in FIG. 1) and described below.

The experimental cigarette BT1, combined a Virginia style tobacco blendcontaining BT treated tobacco (75.4% treated Virginia tobacco, with 4.3%Oriental tobacco and 20.3% untreated Virginia tobacco) with a filtercontaining a CR20 stage (to reduce formaldehyde, acetaldehyde and HCNyields) and a polymer-derived, high activity carbon filter containingstage (to reduce yields of isoprene and other volatile toxicants). Thetarget NFDPM yield from this cigarette was 1 mg under ISO machinesmoking conditions. The experimental cigarette TSS1 was also designed toyield 1 mg of NFDPM under ISO smoking machine conditions and was basedon an US style blend containing TSS (a blend of Virginia, Burley andOriental tobaccos, with the inclusion of approximately 20% TSS and thesame filter used in experimental cigarette BT1. The experimentalcigarette TSS6 also used 20% TSS in a different US style blend, and wasdesigned to give an NFDPM yield of 6 mg under ISO machine smokingconditions. A different filter construction was used with thiscigarette: a dual segment filter containing 80 mg of the high activitycarbon interspersed amongst CA fibres adjacent to the tobacco rod with aCA stage at the mouth end.

The commercial comparator cigarette CC1 contained a US-blended style oftobacco, including some Maryland tobacco. The commercial comparatorcigarette, CC6, was also a typical US-blended cigarette but with adifferent blend to CC1. The design features of the three ECs aresummarised and compared with control cigarettes and commercialcomparators in Table 2 [shown in FIG. 1]. Both commercial comparatorcigarettes used single stage cellulose acetate filters. The three“scientific control” (SC) cigarettes had identical construction to therelevant experimental cigarettes BT1, TSS1 and TSS6, with the exceptionthat the filter used in each control cigarette was a single stage 27 mmCA filter without additional filter adsorbent media.

Table 2 shows that the cigarette constructions of BT1 and CC1 were verysimilar, with well matched filter ventilation and paper permeability.There were slight differences in tobacco density and filter pressuredrop (the draw resistance or impedence to flow of the filter), with BT1higher than CC1 for both parameters. The cigarette constructions of TSS1and CC1 were also very similar. The filter pressure drop was higher fromTSS1 than the commercial control, but both tobacco density and filterpressure drop were higher for CC1. For TSS6 and CC6 less filterventilation was used than with the 1 mg (ISO) products. Comparing thetwo 6 mg (ISO) products showed slightly higher tobacco densities,pressure drop values and slightly lower filter ventilation for TSS6.

2.3 Smoke Chemistry Analysis

Prior to smoke chemistry analysis, cigarettes were conditioned accordingto the specifications of ISO 3402, 1999. Routine chemical analyses wereperformed according to the smoking conditions specified in ISO 4387,2000 (i.e., a 35 ml puff of 2 seconds duration taken every 60 seconds,abbreviated as 35/2/60) and ISO 3308, 2000 which was developed for NFDPMand nicotine analysis.

Approximately 150 smoke constituents have been described as toxicantsand a few regulatory authorities have requested yield data on a subset(approximately 40) of them. Yield restrictions for some of thesetoxicants have been proposed (Burns, D., et al (2008) Mandated loweringof toxicants in cigarette smoke: a description of the World HealthOrganization TobReg proposal. Tob. Control 17, 132-141) along with anapproach to their biomonitoring (Hecht, S. S. et al (2010) Applyingtobacco carcinogen and toxicant biomarkers in product regulation andcancer prevention. Chem. Res. Toxicol. 23, 1001-1008). For these reasonsand in order to characterise the ECs more precisely, the MS yields of anextended range (47 analytes) of smoke constituents were measured. Theother, approximately 100, toxicants not examined in this work were notmeasured due to the lack of available validated analytical methods.Values for benzo(a)pyrene yields were obtained twice, through a directmeasure and also as part of a suite of polycyclic aromatic hydrocarbons(PAHs).

Slight modification to the ISO smoking parameters was required for themeasurement of other analytes, and the current methods are availablefrom British American Tobacco,(www.batscience.com/groupms/sites/BAT_(—)7AWFH3.nsf/vwPagesWebLive/DO7AXLPY?opendocument&SKN=1).Measuring the yield of smoke constituents from a smoking machine doesnot mimic human smoking yields and so all RTPs were tested under a rangeof different smoking machine settings in order to allow machine yieldperformance to be assessed over a wide range of possible smokingconditions. These modified smoking conditions are described in Table 3.

TABLE 3 Smoking machine parameters. Filter Puff Puff Puff Vent SmokingVolume Duration Interval Blocking Description Abbreviation (ml) (s) (s)(%) ISO 3308/4387 ISO 35 2 60 0 Health Canada HCI 55 2 30 100 IntenseHealth Canada HCI-VO 55 2 30 0 Intense-Filter Vents Open ISO WG 9 WG9B60 2 30 50 Intense Option B

Sidestream smoke (SS) yields were also measured as described by HealthCanada, 1999 but only under ISO smoke generation parameters and for awider range of smoke constituents. The SS testing was conducted byLabstat International ULC.

2.4 Statistical Analysis

Statistical comparisons of smoke yields between different cigarettetypes were conducted using a two-tailed, unpaired, Student's t-test,performed with Minitab v16. Levels of significance of P<0.01 and P<0.05are shown and any P value>0.05 is shown as nonsignificant (NS).

For comparisons of individual smoke constituent yields across studies,mean values from published data sets (Health Canada, 2004; Counts etal., 2005; Department of Health Australia, 2002) were examined fornormal distribution using the Anderson Darling statistic. Percentiledistributions within the toxicant data were calculated using anempirical cumulative distribution analysis within Minitab v16.

3. Results and Discussion

Testing of the ECs was conducted in order to examine the actualperformance of the ECs from a blend and smoke chemistry perspective, byquantifying the MS constituents and specific toxicant yields under anumber of machine smoking conditions.

The SS emissions from the ECs were also measured using the ISO smokingprofile. The tests were conducted on a comparative basis with twocommercial cigarettes and with three scientific control cigarettes. As afinal step, the overall performance of the ECs was assessed both incomparison to previously published MS yield data on cigarettes fromseveral countries and as ratios of specific toxicant yields to nicotineyields.

3.1 Mainstream Smoke Constituent Yields

The yields of the major smoke constituents (NFDPM, nicotine and CO) andglycerol under four smoking machine conditions are shown in Table 4(shown in FIG. 2). Glycerol measurements are included in this tablebecause it has been incorporated into the tobacco-substitute sheet usedin the ECs TSS1 and TSS6, to dilute other smoke constituents in thesmoke particulate phase.

Table 4 shows that BT1 and CC1 were well matched across the four smokingregimes for MS NFDPM and nicotine yields, but that BT1 had lower COyields than CC1. TSS1 and CC1 were well matched across the four smokingregimes for NFDPM and nicotine yields but TSS1 had lower CO yields thanCC1. The higher glycerol yield from TSS1 is consistent with the intendeddilution effect due to the glycerol content of TSS. The MS NFDPM andnicotine yields from TSS6 and CC6 were well matched across the foursmoking regimes, other than higher CO yields from CC6 and the expectedhigher glycerol yields from TSS6.

For these major smoke analytes the yields measured followed the samerank order based on smoking machine conditions: ISO<HCI-VO<WG9B<HCI. Theyield differences between the different regimes were substantiallygreater with the 1 mg products than with the 6 mg products, as the levelof ventilation was higher and the impact of ventilation blocking for theWG9B and HCI regimes is therefore more profound for the 1 mg products.For the 6 mg products the differences in the major smoke measures(NFDPM, nicotine and CO) between some of the regimes were small (in theorder of 5-10%).

The 47 toxicants quantified in this work were also measured under all ofthe smoking machine conditions shown in Table 3, except that data forthe ECs TSS1 and BT1 under ISO machine smoking conditions were notcollected because preliminary runs showed the yields of manyconstituents to be below the LOQ for the methods. The machine smokedyields of these toxicants generally followed the rank order noted forNFDPM, nicotine and CO shown in Table 4 and so, for the remainder ofthis paper, only the yields obtained under HCI conditions are described.Some consistent exceptions to the general yield trend were observed.With all products the volatile phenols, quinoline, and fluorene did notincrease systematically with increasing intensity of the smoking regimeand the yields of the major smoke measures; arsenic, phenanthrene andthe measure for benzo(a)pyrene from the PAH suite also displayed thisbehaviour for the majority of the products. In particular the yields ofthese species were greater under the WG9B regime than with the HCIregime despite the greater overall amounts of smoke generated by the HCIregime. Volatile phenols are known to be selectively removed from smokeby cellulose acetate filters; the consistent behaviour observed here mayrepresent some change in filtration efficiency for these species betweenthe WG9B and HCI regimes. Alternatively it may represent some analyticalweakness with the measurement method at high intensity smoking regimes.Similar changes were observed on a more occasional basis for someanalytes (e.g. 1,3-butadiene yields with CC1 were lower than expectedfrom the trends across smoking regimes found for the other fiveproducts); this was found in particular with the 6 mg products whensimilar amounts of NFDPM were generated between the different smokingregimes, and these observations are likely due to analytical errors, orreflect limits in the discriminatory power of the analytical techniques.

The use of the HCI smoking regime in this work represents the strictesttest of the ECs and the commercial comparator cigarettes. Although thesesmoking conditions inactivate a design feature used in the ECs andcommercial cigarettes (filter ventilation), they address criticism ofthe machine yield values obtained from ventilated cigarettes.

3.1.1 Metal and TSNA Yields

Two groups of toxicants included on regulatory lists are the metals andthe tobacco specific nitrosamines (TSNAs). Both these groups oftoxicants are primarily affected by the tobacco blend used in cigarettemanufacture and so careful blend selection is a major contributor totheir reduction in smoke. The chemical analysis of blend metals andTSNAs are described in Table 5 (shown in FIG. 3) and their MS yieldsunder HCI smoking machine conditions are shown in Table 6 (shown in FIG.4). The yields are discussed for each EC in Sections 3.1.2.1 to 3.1.2.3below.

3.1.2 Other Toxicant Yields

Smoke constituent yield comparisons between ECs and commercial controls,under HCI smoking machine conditions, are shown in Table 7 (shown inFIG. 5). The yields are discussed for each EC in Sections 3.1.2.1 to3.1.2.3 below.

3.1.2.1 BT1

Measurement of blend chemistries (Table 5) showed the blend arsenic andchromium contents of BT1 were statistically significantly higher thanthe commercial cigarette CC1; whereas lead and nickel contents of theBT1 blend were lower. The MS yields for metals from BT1 were comparableto or lower than the yields from CC1, except that the arsenic andmercury yield were higher. The higher arsenic yield may be explained bythe higher blend content of this metal but the mercury yield is notexplained by blend content and may represent an artefact because the BT1blend content of mercury was comparable to or lower than CC1, beingbelow the LOQ for this metal (Table 5).

Blend nitrosamine content of BT1 was lower than US-blended commercialcomparator CC1, as has been seen previously in comparison of Virginiaand US-blended cigarettes. The MS yields of nitrogenous constituentswere expected to be lower from BT1 than from CC1 for two reasons: firstthe tobacco treatment reduces precursors of nitrogenous smoke compounds;and, second, Virginia style tobaccos typically generate lower yields ofnitrogenous smoke constituents than US-blended cigarettes. Measurementof the yields of nitrogenous compounds showed the anticipateddifferences: yields of the TSNAs were statistically significantly(83-96%) lower from BT1 than from CC1 (Table 6); aromatic amine yieldsfrom BT1 were 26-57% lower than from CC1 (Table 7); and the yields ofother nitrogenous compounds from BT1 were also substantially lower (HCNby 82%, NO by 79%, ammonia by 75%, pyridine by 97%, quinolene by 67% andacrylonitrile by 69%) than the respective yields from CC1 (Table 7).These data confirm that the blend selection, use of the BT process (andincorporation of CR20 in the filter in the case of HCN yields) producedthe expected lower yields of toxicants from the EC.

The BT process also reduces blend polyphenol levels and so reductions inMS phenols yields would be expected; however, higher yields of phenolicsare generally expected from Virginia style products than from US-blendedproducts and this tobacco type difference could mitigate any reductionsfrom the BT process. Comparison between phenolic compound yields fromCC1 and from BT1 showed a mixed picture: phenol, p-cresol and resorcinolyields were lower from BT1, whereas m-cresol, catechol and hydroquinoneyields were higher from BT1 (Table 7).

The BT process does not influence benzo(a)pyrene yields and analysis ofPAHs in the current study showed comparable yields from BT1 and CC1 forfluorene, phenanthrene, pyrene and benzo(a)pyrene. Lower carbonyl yields(26 to 74% lower) were obtained from cigarette BT1, apart fromformaldehyde, which showed a higher (41%) yield from BT1. The volatilehydrocarbon yields from BT1 were lower, with a range from 21 to 78% forisoprene, benzene, toluene and naphthalene, when compared to therespective constituent yields from CC1; however, the 1,3-butadiene yieldwas 35% higher from BT1 compared to CC1. The 1,3-butadiene yields fromCC1 are lower than expected under the HCI regime, and this observationmay therefore be unreliable. Most of the observed differences involatile constituent yields are consistent with the use of an effectivevapour phase adsorbent in the filter of BT1. Formaldehyde yields aredriven in part by sugar levels, which are normally higher in Virginiablends than in US blends. Formaldehyde yields are also increased by theblend treatment process. Hence the higher formaldehyde yields from BT1are understandable on the basis of knowledge of formaldehyde generationin cigarettes. The apparent higher yield of 1,3-butadiene from BT1 ispossibly due to an error in the yield measurement of CC1 as there is noobvious mechanistic factor to support this difference (the tobaccotreatment process does not give statistically significant changes in1,3-butadiene yields and the use of the vapour phase adsorbent in BT1filters should result in lower 1,3 butadiene yields from BT1). Thecontribution of the blend and the selective filter used in BT1 to theoverall reductions in smoke toxicants are addressed in Section 3.2 andthe results are consistent with the higher yield values for formaldehydeobserved in Table 7 being due to blend chemistry factors.

3.1.2.2 TSS1

The overall blend metal content was higher in TSS1 than in CC1 for somemetals (arsenic, chromium and nickel), lower for cadmium content and notdifferent for other metals (Table 5). The TSS contains a high proportionof chalk, which would contribute some portion of the blend metals.Analysis of the TSS showed a higher level of chromium and comparable orlower levels of the other measured metals than the TSS1 blend. Hence,the higher chromium content of TSS1 than CC1 most likely reflects theinclusion of TSS material in the blend; whereas, the higher arsenic andnickel levels were most likely due to the different tobacco types usedin the blend. It should be noted that the transfer of metals from theTSS would not necessarily occur with the same efficiency as fromtobacco, due to possible differences in the chemical form (and thereforevolatility) of trace metals in chalk and in tobacco. Thus, the metalyields in MS under HCI smoking machine conditions were either lower ornot statistically significantly different when TSS1 was compared to CC1(Table 6). The blend nitrosamine content of TSS1 was lower (23-72%) thanthat of CC1 (Table 5) and the MS yields of the TSNAs under HCI machinesmoking conditions were correspondingly lower (17 to 69%) for TSS1 thanCC1 (Table 6).

Statistically significantly lower yields were found from TSS1 than fromCC1 for most of the phenolics (29-57%), carbonyls (44-86%), PAHs (8 to71%) and miscellaneous volatile constituents (27 to 94%); although forcatechol, hydroquinone and benzo(a)pyrene, these differences did notachieve statistical significance (Table 7). These data demonstrate lowertoxicant yields from TSS1 across all of the analyte classes examined,and therefore support the expectation that the TSS, and the three stagefilter, should function to give overall MS toxicant yield reductions inan EC.

3.1.2.3 TSS6

The blend metal contents of TSS6 and CC6 were similar, other thanstatistically significantly higher chromium and cadmium blend levels inTSS6. As noted above, the higher chromium level was most likely due tothe high inorganic content of the TSS; whereas, the higher cadmiumcontent most likely reflects a difference in the tobacco types usedbetween the two blends. The MS yields of cadmium and chromium,determined under HCI smoking machine conditions, were not elevated inTSS6 compared to CC6 (Table 6), which again supports the contention thatthe chemical form of these metals was different between the EC and thecommercial comparator, and less likely to transfer into MS.

The blend nitrosamine contents were lower (39 to 54%) from TSS6 thanthose measured for the CC6 blend (Table 5). Again, this lower blendnitrosamine content translated to 37 to 50% lower MS yields for theseTSNAs under HCI smoking machine conditions (Table 6).

The MS yields from TSS6, across all of the other chemical classesmeasured (aromatic amines (13-20%), phenolics (8-32%), carbonyls(35-85%), PAHs (18-81%) and miscellaneous volatile toxicants (41-96%))were statistically significantly lower than the yields from CC6, exceptfor 1- and 2-aminonaphthalene and m- and p-cresol where the values werenot significantly different and for ammonia where the higher yield (13%)was not statistically significantly different to that of CC6 (Table 7).These data again demonstrate reductions in all classes of measuredtoxicants, and therefore it is apparent that the TSS is functioning asexpected in the EC, to give overall MS toxicant yield reductions.

3.2 Filter Comparisons

From the MS yield data shown in Table 7 all the ECs gave lower yields ofcarbonyls and vapour phase constituents than the respective commercialcomparator cigarettes, with the exception of formaldehyde and1,3-butadiene yields for BT1. To understand better the contribution ofthe blend and the selective filters used in the ECs to the overallreductions in these smoke constituents, direct comparisons were madebetween the ECs and control cigarettes (SC-BT1, SC-TSS1 and SC-TSS6),which were identical in all aspects to the appropriate EC, except forthe use of a mono-stage CA filter without adsorbents. The comparisons ofthe yields from EC and control cigarettes for the carbonyls and othervapour phase constituents are shown in Tables 8 and 9 (shown in FIGS. 6and 7, respectively).

From these data it is clear that the yields of the carbonyls and theother vapour phase constituents were all reduced by the presence of thetriple stage filter containing CR20L and high activity carbon used inECs BT1 and TSS1 (Table 8). The mean change in MS yield across allvolatile constituents measured from BT1 was a reduction of 50% comparedto the control cigarette SC-BT1, with a range of 23% reduction foracetaldehyde to 79% reduction for crotonaldehyde. Very similarreductions were obtained with TSS1, which gave a mean reduction of 50%,with a range from 10% reduction in formaldehyde yield to 79% reductionfor crotonaldehyde yield in comparison to SC-TSS1.

From Table 9 it is apparent that the dual filter containing additionalpolymer derived carbon but without the CR20L resin (as used in TSS6),also reduced the yields of the vapour phase smoke constituents by a meanof 48%, with a range from 11% reduction in acetaldehyde yield to 79%reduction for crotonaldehyde yield. Together, these data confirm thatthe selective filters used in the ECs removed substantial quantities ofvolatile smoke constituents from cigarette MS, confirming previousstudies with the filter adsorbents. For all of the ECs, the MS yields ofboth formaldehyde and 1,3-butadiene were lower than measured with thescientific control cigarettes. The superior performance of the CR20Lresin compared to the high activity carbon at formaldehyde removal fromMS can be seen by the greater reduction in the yield of formaldehydefrom a higher starting value (53 μg/cig or 53%) in the BT1/SC-BT1 paircompared to the 1.9 μg/cig reduction (10%) found with the TSS1/SC-TSS1pair. Thus, it is clear that the greater formaldehyde yield seen whencomparing BT1 with the commercial cigarette CC1 (Table 7) must be due todifferences in blend between these cigarettes. A similar comparison alsoconfirms that the higher 1,3-butadiene yield from BT1 compared to CC1 ismost likely due to an analytical error in the measurement of 1,3butadiene with CC1.

3.3 Comparison of EC Toxicant Yields with Those from Published CigaretteBrand Data

This paper has focused on a comparison of EC toxicant yields with theyields from two commercial comparator cigarettes. However, to fullyestablish whether the ECs offer reduced machine yields in comparison toconventional commercial cigarettes it is necessary to compare theiryields with those from a wider range of cigarettes. The absolute yieldvalues of the ECs described here can be compared with other publisheddata obtained under HCI smoking conditions, namely: (1) (Health Canada(2004) Constituents and emissions reported for cigarettes sold in Canadahttp://www.hc-sc.gc.ca/hc-ps/alt_formats/hecs-sesc/pdf/tobactabac/legislation/reg/indust/constitu-eng.pdf(accessed November 2010); data received on request fromTRR_RRRT@hc-sc.gc.ca; (2) Counts, M. E. et al. (2005) Smoke compositionand predicting relationships for international commercial cigarettessmoked with three machine-smoking conditions. Regul. Toxicol. Pharmacol.41, 185-227; and (3); Department of Health Australia and Ageing:http://www.health.gov.au/internet/main/publishing.nsf/Content/tobacco-emis,(accessed, November 2010). It should, however, be noted that suchcomparisons must be treated with caution due to the known difficultiesbased on limited standardisation between laboratories for the analysisof smoke constituents other than NFDPM, nicotine and CO.

The three data sources above were compiled into one dataset to provide areference set of global cigarette yield data with which to compare thetoxicant yields from the ECs described in this study. The full datasetwas truncated as follows: first, arsenic, methyl ethyl ketone, nickeland selenium yields were removed from the dataset because yields werenot provided by all three sources; second, a number of brands wereremoved from the dataset due to incomplete, duplicated or erroneous data(two brands in the HC dataset appear to have erroneous (exchanged)toluene and styrene yields; tar, nicotine and CO yields were notprovided in the HC dataset for Gitanes KS, and multiple instances of thesame yield data were observed in the HC dataset). Finally, referenceproducts were removed from the dataset to ensure that only commercialbrands were included. This resulted in a dataset of 120 cigarette brandscovering 16 countries or regions. While extensive it is unlikely thatthis dataset is fully representative of the range of cigarette productson-sale globally, either with respect to the range of design features,or as a representative sample of global brands. However, while it islimited in these respects, it does constitute a valid comparator set forthe toxicant yields for these ECs.

The data was examined to see if it was normally distributed; while anumber of toxicants in the dataset were normally distributed themajority (and in particular nitrogenous toxicants such as TSNAs andaromatic amines) were not. Consequently the reference dataset wassubject to an empirical cumulative distribution analysis, producing apercentile distribution within the toxicant yields. Yields from the ECswere then compared to the empirical cumulative distribution to identifythe position of these yields in comparison to the commercial brands(FIGS. 8 and 9). In these comparisons, the yields of the ECs describedhere fall at the low end of the range for numerous toxicants and oftengive lower values for specific toxicants than any of the products in thecommercial brand dataset. Exceptions to this are catechol yields fromBT1 and NO and TSNA yields from TSS1 and TSS6, where the yields areapproximately equivalent to the median values for the commercial productdataset. In contrast, the yields of the commercial comparator cigarettesCC1 and CC6 are generally distributed over the range of yields observedwith the commercial dataset.

A further comparison was conducted, examining the total toxicant levelsfrom the ECs and each of the commercial products in the dataset. Thiswas conducted in three ways. The first method was to sum the yields ofthe 39 toxicants for each cigarette to give a total toxicant yield (TTY)for each brand. This approach is of limited utility because the TTYvalue for each brand is dominated by tar, CO and nicotine, and manyother toxicants do not contribute significantly to the total value. Asecond approach was to sum the yields of all toxicants (but excludingtar, nicotine and CO yields) for each cigarette to give a total for thetoxicant subset of yields (TSY). A third, normalisation method gavegreater insight into the contribution of all toxicants, wherein a medianvalue was calculated for each toxicant in the commercial dataset. Themedian value was normalised to 100 for each toxicant, and the yields oftoxicants scaled against this value of 100. Totaling the scaled valuesfor all toxicants gave a normalised toxicant total (NTT) for each brand.The TTY, TSY and NTT values for the ECs are compared to and rankedagainst the values for all of the brands in the commercial dataset inFIGS. 10 to 12. The comparisons show, with each of the approaches, thatthe ECs were at the low end of the ranking order. The 1 mg ECs werefound to have the lowest total toxicant yields under each of the threeapproaches, and the 6 mg EC was also lower than any of the commercialbrands for the TSY and NTT. In the TTY analysis two of the 120commercial products have lower TTY values than TSS6 due to their lowertar and nicotine values. The commercial comparator cigarettes CC1 andCC6 were also reasonably low in total toxicant values in comparison withthe dataset of commercial brands, falling around the lower quartile ofvalues.

Together these analyses show that the ECs offer some of the lowestmachine toxicant yields of cigarettes for which published HCI smokechemistry is available; these comparisons therefore confirm that the ECsgenerate reduced machine toxicant yields in comparison to known levelsof commercial cigarettes.

3.4 Comparisons of EC Yields as a Ratio to Nicotine Yields

The analysis described above is restricted to assessment of machineyields of toxicants. However, it has been proposed that the ratio ofsmoke toxicants to the MS nicotine yield of cigarettes gives a betterpredictor of smokers' exposure to the toxicant than the MS yield valuealone. Therefore, the ratio of MS constituents yields measured in thisstudy to the MS nicotine yields, all measured under HCI smoking machineconditions, has been calculated and is given as a supplemental table(Table 10, FIGS. 8A and 8B). Under Health Canada Intense machine smokingconditions, the NFDPM yields from BT1, TSS1 and CC1 were comparable, butthe nicotine yield from BT1 was slightly higher and the nicotine yieldfrom TSS1 slightly lower than from CC1 (Tables 4 and 7). When the yieldvalues for the EC were calculated as a ratio to the nicotine yield, andcompared to those from CC1 and CC6, they followed the same trends asfound when comparing the yields per cigarette, but the lower values fromBT1 when compared to CC1 are more pronounced and the lower values fromTSS1 when compared to CC1 are slightly less pronounced.

3.5 Sidestream Smoke Yields

To complete the chemical analysis of smoke emissions from the EC, SSyields for the expanded list of smoke constituents were measured, underISO smoking parameters. The ISO smoking parameters were chosen becausethey generate higher SS yields than any of the other smoking regimes. Ingeneral, under any smoking regime, the quantity of sidestream smoke canbe expected to be dependent on the amount of tobacco consumed in thestatic burn or smoulder phase of cigarette smoking. The SS yield resultsare presented as a comparison between the ECs BT1 and TSS1 and thecommercial cigarette CC1, in Table 10.

Statistically significantly higher yields of sidestream NFDPM (21%), andseveral constituents such as benzo(a)pyrene (28%), phenolics (28-77%),carbonyls (22-63%) and volatile hydrocarbon (20-24%) constituents werefound with BT1 than from CC1. In contrast lower yields of nitrogenous SSsmoke constituents such as TSNAs (31-82%), HCN (47%), aromatic amines(21-40%) nitrogen oxides, pyridine and quinolene (19-35%) were foundwith BT1 than with CC1. Most of these changes were described previously(Liu et al, 2010), however, the higher SS phenolic yields and lower thananticipated TSNA yields from BT1 suggest that chemical differencesbetween Virginia and US-blended tobaccos also influence the SS yields ofindividual constituents. Finally, the 13% higher tobacco weight from BT1than from CC1 will also contribute across the board to the observedincreases.

Many SS smoke constituent yields were lower from the EC cigarette TSS1than from CC1. The greatest numerical differences in SS yields wereobserved for the TSNAs which were 28 to 52% lower from TSS1 than CC1;these observations are consistent with the observed trends in MS yieldsof these species. The wide range of reductions most likely reflects thereduction in tobacco mass in the cigarettes to resulting fromincorporation of the TSS, and consequent decrease in the total amount ofsmoke generated. The one constituent with a statistically significantlyhigher sidestream yield from TSS1 than from CC1 was formaldehyde (19%higher). Higher SS formaldehyde yields were also observed with higherlevels of TSS inclusion in the blend (McAdam et al, 2010), suggestingthat formaldehyde might be a combustion by-product of the organicmaterials used in TSS manufacture.

4. Conclusions

Three ECs were made using a combination of technological approaches, andchemical testing under four different machine smoking parameters hasconfirmed overall reductions of MS toxicants yields from the ECs. Whencompared with published values of MS toxicant yields from conventionalcigarettes, despite elevated formaldehyde yields with BT1, theperformance of these ECs appears to be superior, even if they are rankedon a nicotine ratio basis. The data presented in this study support adesignation of these ECs as reduced machine-yield prototypes, andprevious data with EC made using the TSS approach suggest that lowerbiomarkers of exposure to MS toxicants could be achieved with theseRMYPs when used by smokers.

Despite the low overall machine yields of toxicants obtained from thecurrent RMYP and their performance against commercial comparators andother published toxicant yield data, substantial amounts of scientificdata would need to be acquired, including biomarkers of exposure andbiomarkers of biological effect, to determine whether such productsmight be associated with lower health risks, and therefore there is nocertainty that these RMYP will meet the IOM definitions of a PREP.

Nonetheless, we believe that the results from this study are sufficientto encourage further work, including human biomarker studies of theseRMYP and further application and refinement of the technologies used intheir manufacture.

5. Prototype Smoking Articles

Three prototype RTP smoking articles were produced according to thepresent invention. The cigarettes are of king size format with a filterlength of 27 mm and a tobacco rod of 56 mm. The prototypes have atobacco rod comprising a mix of lamina, Expanded Tobacco and non tobaccosheet or modified tobacco. Conventional cigarette paper is used to formthe tobacco rod and ensure the achievement of burn rate and subsequentpuff number.

The filter for two of the prototypes is a triple filter composed of a CAmouth end segment (7 mm in length), a CA central segment containing CR20HD ion exchange resin (10 mm in length) and a dalmation style tobaccoend segment containing carbon beads with an engineered microstructure(10 mm in length). The filter for the third prototype is a dual filtercomposed of a CA mouth end segment (15 mm in length) and a dalmationstyle tobacco end segment containing high activity, polymer-derivedcarbon beads (12 mm in length).

The prototype cigarettes were manufactured to give ISO NFDPM yields of 1(T562 and H671) and 6 mg (F752). The specification of the prototypecigarettes is described in more detail in Tables 11 to 13.

TABLE 11 Tobacco blend specifications Prototype T562 (1 mg) H671 (1 mg)F752 (6 mg) Lamina (% wwb) 40 12.5 55.0 Expanded Tobacco^(a) 40 12.5 —(% wwb) Expanded Tobacco^(b) — — 25.0 (% wwb) Modified Tobacco^(c) (%wwb) — 75 — Non tobacco sheet^(d) (% wwb) 20 — 20 Added Top Flavour 0.80.8 0.8 (AWOLSA) (% wwb) ^(a)Aurora - 100% flue cured tobacco ^(b)SCB -50% flue cured, 50% Burley ^(c)Tobacco processed using the tobacco blendtreatment ^(d)The non tobacco sheet is TSS with the followingspecification: Chalk (78.5%), Kelvis Alginate (7.5%), Glycerol (12.5%)and Caramel colourant (1.5%) (manufacturer; Deli-HTL).

TABLE 12 Cigarette specifications Prototype T562 (1 mg) H671 (1 mg) F752(6 mg) Circumference (mm) 24.6 24.6 24.6 Total length (mm) 83 83 83Tobacco rod length (mm) 56 56 56 Cigarette paper CP 50-23 CP 50-23 CP50-23 VGM VGM VGM 2.0 KCM 2.0 KCM 2.0 KCM Ventilation type OML OML OMLVentilation total 80 80 46 (ST + OML) (%) Density (mg/cc) 216 247 235Cigarette pressure drop 97 91 109 (mmWG) Cigarette firmness (%) TBC TBCTBC Tar (NFDPM) (mg) 1.0 1.2 5.3 Nicotine (mg) 0.08 0.10 0.43 Carbonmonoxide (mg) 1.0 1.0 4.9

TABLE 13 Filter specification Code T562 (1 mg) H671 (1 mg) F752 (6 mg)Filter Code (Filtrona, SAM 013108- SAM 013108- SAM USA) 031 031020608-040 Total length (mm) 27 27 27 Mouth end segment  7  7 15 length(mm) Central segment length 10 10 — (mm) Tobacco segment length 10 10 12(mm) Mouth end segment tow Mono CA Mono CA Mono CA Central segmenttow^(a) CA + 20 mg CA + 20 mg — CR20 HD CR20 HD Tobacco end segment CA +60 mg CA + 60 mg CA + 80 mg tow^(b) Blucher carbon Blucher carbonBlucher carbon Total filter PD (mmWG) 150  142  114  Plugwrap^(c)PW600043 PW600043 PW600043 ^(a)CR20 HD = amine functionalised resin(manufacturer: Mitsubishi) ^(b)Blucher carbon = spherical carbon beads(manufacturer: Adsor Tech.) ^(c)Plugwrap for completed Dual or Triplefilter

6. Smoke Toxicant Exposure Study

This study looked at the evaluation of biomarkers of exposure (BoE) totoxicants in smokers who switched from conventional cigarettes toreduced toxicant prototype (RTP) cigarettes according to the presentinvention.

The technologies discussed in detail above were combined to produce one6 mg and two 1 mg ISO tar yield RTPs as detailed in Table 14 below.

TABLE 14 Tested prototype products ISO* tar yield HCI# tar Productidentifier & Tobacco Tobacco target yield description blend filter(actual) (actual) CC6 100% US Single 6 mg (5.0 mg) 24.4 mg Control basedon 6 mg style tobacco segment: ISO conventional blend CA cigarette TSS680% US style Dual 6 mg (5.3 mg) 20.7 mg 6 mg ISO tar tobacco segment:prototype blend CA + 20% tobacco Carbon substitute (80 mg) sheet CC1100% US Single 1 mg (1.2 mg) 18.9 mg Control based on 1 mg style tobaccosegment: ISO tar commercial blend CA cigarette TSS1 80% US style Triple1 mg (1.0 mg) 17.3 mg 1 mg ISO tar tobacco segment: prototype blend CA +20% tobacco Carbon substitute (60 mg) + sheet Resin (20 mg) BT1 25%Virginia Tiiple 1 mg (1.2 mg) 17.8 mg 1 mg ISO tar style tobaccosegment: prototype with blend CA + tobacco blend (untreated) Carbonmodification 75% Virginia (60 mg) + style tobacco Resin (20 mg) blend(treated) *ISO regime = 35 mL puff volume, 2 second duration, 60 secondinterval, filter ventilation 100% open # HCI (Health Canada Intense)regime = 55 mL puff volume, 2 second duration, 30 second interval,filter ventilation 100% blocked

Smoke chemistry indicated good reductions in toxicants compared tocontrol cigarettes of conventional design, see Table 15 (FIG. 15).

A six week single-centre, single-blinded, randomised controlledswitching study with occasional clinical confinement, as illustrated inFIG. 16, was conducted. A total of 301 healthy adult subjects wererecruited into the study; 100 smokers of 6-7 mg ISO tar yield cigarettes(assigned to the 6 mg groups), 151 smokers of 1-2 mg ISO tar yieldcigarettes (assigned to the 1 mg groups) and 50 non-smokers. Recruitedsmokers were randomly assigned to a control or test group within theirtar band, with approximately 50 per group. All smokers smoked a suppliedcontrol product for 2 weeks after which Day 14 baseline measurementswere made. Control group smokers continued to smoke the control productfor a further 4 weeks, while test group smokers were switched to an RTPfor 4 weeks. In each case, measurements were made at Days 28 (two weeks)and 41 (four weeks). The non-smoker group provided an indication ofbackground levels of biomarkers.

Collection of 24 hour urine samples occurred during three (for smokers)and two (for non-smokers) short periods of clinical confinement (seeFIG. 16), and exposure to a number of smoke constituents was estimatedby analysis of levels of urinary biomarkers of exposure. Analysis ofbiomarkers of exposure was achieved using validated LC-MS/MS methods.

When the RTP smoke chemistry was compared to that of the controlcigarette, most measured toxicants were substantially lower (10-96%)with actual levels dependant on design and toxicant (see Table 15). Theonly higher yields were for one product (BT1) which delivered 16% morenicotine and 35% more 1,3-butadiene, although this was also the productthat showed the greatest overall reductions for all other toxicants.Direction and relative magnitude of changes in corresponding biomarkerswere largely in-keeping with the changes in smoke chemistry (Table 15and FIGS. 17 and 18) although in a few cases a reduction in the smokewas accompanied by an increase in the biomarker (nicotine and NNK forTSS1) or an increase in the smoke but a reduction in biomarker(1,3-butadiene for BT1). Reasons for these discrepancies are unknown,but may involve analytical variability or smoker behaviour.

FIG. 17 shows the biomarker results for Group 2 who switched fromcontrol cigarette CC6 (Day 14) to test cigarette TSS6 (Day 41). *denotes a statistically significant difference (p≦0.01) between day 14and 41 results. Non-smoker biomarker levels are shown for reference. Allnon-smoker levels were significantly lower than day 14 values

FIG. 18 shows the biomarker results for Group 4, who switched fromcontrol cigarette CC1 (Day 14) to test cigarette TSS1 (Day 41) and Group5, who switched from control cigarette CC1 (Day 14) to test cigaretteBT1 (Day 41).

The study found that, on average, groups of cigarette smokers whoswitched to reduced toxicant prototype cigarettes had reduced levels inthe corresponding biomarker of exposure (BoE). These included BoEs forparticulate and vapour phase toxicants. Different prototypes resulted indifferent levels of reductions to the BoE, in some cases with reductionssubstantially greater than 50%, depending upon which combination oftechnologies was used. Generally most of the reduction in biomarkerlevel was apparent two weeks after switching. In all cases the averagebiomarker level was lower in the non-smoker group

This study demonstrates for the first time significant reductions in arange of BoE of tobacco smoke toxicants in smokers following a switchfrom conventional cigarettes to reduced toxicant prototype cigarettesaccording to the present invention.

FIG. 19 shows a smoking article design according to an embodiment of thepresent invention. The smoking article 1 comprises a tobacco rod 2 and afilter 3. The tobacco rod comprises a rod of smokable material, thecomposition of which is 75% blend treated tobacco, 12.5% leaf and 12.5%expanded tobacco.

The blend treated tobacco is a tobacco with reduced protein andpolyphenol content which results from the following process: (i) aqueousextraction of a tobacco; (ii) passing the aqueous extract through a clayand a resin; (iii) treatment of the fibre with an enzyme anddeactivation; and (iv) recombining the extract and fibre and drying. Theleaf is tobacco as is used in conventional commercial cigarettes. Theexpanded tobacco is a tobacco that has been expanded using asupercritical CO₂ process which is used in conventional commercialcigarettes.

The filter 3 is attached to the tobacco rod 2 by a tipping paper whichis a non-porous paper.

The filter 3 is made up of three sections, as indicated by the inset.The section 4 adjacent the end of the tobacco rod is 10 mm in length andcontains 60 mg of synthetic carbon. This is a form of carbon which hasan engineered porous structure. The middle section 5 is 10 mm in lengthand contains 20 mg (that is, 2 mg/mm) of CR20HD, an amine functionalizedresin having a water content of 12-17%. The mouth-end section 6 of thefilter is 7 mm in length. This may comprise, for example, celluloseacetate tow as used in conventional commercial cigarettes.

In possible variations of the smoking article design shown in FIG. 19,the smokable material may further include tobacco substitute sheet.Tobacco substitute sheet is a chalk-based sheet containing glycerol thatreduces the quantity of tobacco in a cigarette when incorporated intothe tobacco blend. The tobacco substitute sheet may replace some or allof any or all of the different materials making up the smokable materialof the smoking article design discussed above.

A further variation may be to use CR20D in the filter. CR20D is an aminefunctionalized resin having a water content of 0-5%. For example, CR20Dmay partially or completely replace the CR20HD used in the designdiscussed above.

The foregoing description and examples have been set forth merely toillustrate the invention and are not intended to be limiting. Sincemodifications of the described embodiments incorporating the spirit andsubstance of the invention may occur to persons skilled in the art, theinvention should be construed broadly to include all variations withinthe scope of the appended claims and equivalents thereof.

1. A smoking article comprising: a tobacco blend comprising one of: atleast one tobacco; and at least one tobacco grade; said one of at leastone tobacco and at least one tobacco grade having at least one of lowTSNA and metal content; and a high activity carbon comprising asynthetic polymer-derived carbon material; further comprising at leastone of: a tobacco blend that has been treated to remove at least one ofpolyphenols and peptides; and a tobacco substitute sheet comprising anon-combustible inorganic filler, a binder and an aerosol generatingmeans;
 2. The smoking article as claimed in claim 1, further comprisinga rod of smokable material comprising up to 60% tobacco substitutesheet.
 3. The smoking article as claimed in claim 2, further comprisinga rod of smokable material comprising 20% tobacco substitute sheet and80% tobacco.
 4. The smoking article as claimed in claim 1, furthercomprising glycerol.
 5. The smoking article as claimed in claim 1,further comprising a rod of smokable material comprising up to 100%treated tobacco blend.
 6. The smoking article as claimed in claim 5,further comprising a rod of smokable material comprising 75% treatedtobacco blend and 25% tobacco.
 7. The smoking article as claimed inclaim 1, further comprising a filter having three sections, a mouth endstage comprising cellulose acetate, a middle stage comprising celluloseacetate and an amine-functionalised chelating resin, and a tobacco endstage comprising cellulose acetate and high activity carbon.
 8. Thesmoking article as claimed in claim 7, wherein the middle stagecomprises 20 mg of an amine-functionalised chelating resin.
 9. Thesmoking article as claimed in claim 7, wherein the tobacco end stagefurther comprises 60 mg carbon.
 10. The smoking article as claimed inclaim 1, further comprising a filter having two sections, a mouth endstage comprising cellulose acetate, and a tobacco end stage comprisingcellulose acetate and carbon.
 11. The smoking article as claimed inclaim 10, wherein the tobacco end stage further comprises 80 mg carbon.12. The smoking article as claimed in claim 7, wherein the carboncomprises high activity carbon beads comprising a polymer-derived carbonmaterial.
 13. The smoking article as claimed in claim 7, wherein theamine-functionalised chelating resin is CR20.
 14. A smoking articlecomprising: a tobacco blend comprising one of: at least one tobacco; andat least one tobacco grade; said one of at least one tobacco and atleast one tobacco grade having at least one of low TSNA and metalcontent; a high activity carbon comprising a synthetic polymer-derivedcarbon material; a tobacco blend that has been treated to remove atleast one of polyphenols and peptides; a tobacco substitute sheetcomprising a non-combustible inorganic filler, a binder and an aerosolgenerating means; and an amine-functionalised chelating resin.
 15. Thesmoking article as claimed in claim 1, configured to exhibit a reductionin yield in all mainstream smoke constituents considered to beundesirable of at least 10%.
 16. The smoking article as claimed in claim1, further comprising an amine-functionalised chelating resin.